In robotic packaging operations, a producer might desire to ship work products in shipping containers of a standard shape and size. The shape and size of the individual work products might be different from one job to the next. In order to ship in standard size containers it may be required to retrieve and collect the products of one size and shape on the end effector of the robot in a different pattern than for other products.
For example, in the bakery industry a producer typically will produce several sizes of loaves of bread from time to time and have one basket size in which the producer ships the products. The different size products may fit best in the basket when configured in different arrangements or pack patterns than other sized products. The pack patterns are dependent on the product sizes. A robot may be used to pick the products up from a line of the products with multiple picks of the end effector of the robot at various orientations of the end effector with respect to the line of products to form the desired pattern of the products on the end effector. Once loaded with the work products in the desired pattern, the robot moves the end effector to the basket and the robot then deposits the products into the basket all at once in the desired pattern.
Usually a single vacuum source with high flow and low vacuum level for the pick-up force is desirable and most commonly used. The end effector may include multiple vacuum retrievers in the form of bellows suction cups as the vacuum retrievers to provide the seal between the vacuum source and the objects being picked. When multiple picks are required to form the desired pattern of products for one delivery of the products to the basket, the vacuum must be applied to certain suction cups on the end effector to enable picking or holding of the product in that pick group while other groups of the suction bellows must not allow vacuum flow because those zones of the end effector either are not yet covered by work products or the positions are to be left empty. To accomplish this, the vacuum source may be split in several tubes and then the tubes are valved open or closed to allow vacuum to flow to different sectioned-off portions of the suction surface of the end effector.
The system described above is not ideal when several different groups of retrievers are required to conduct the picking functions and/or the groups of retrievers must change in shape for picking different products. If there are too many pick groups of vacuum retrievers then the vacuum lines become small and restrict the vacuum flow.
A common solution was to provide multiple end effectors that have 2 to 6 pick groups in the suction surface strategically placed for the specific pattern or similar patterns that it is designed for. This is cost prohibitive as some producers may have many different shaped and sized products and would require many different end effectors.
Similarly, another method of having a non-grouped end effector was to have the vacuum source connected with a large hose to a large plenum. The bottom of the plenum is then populated with multiple suction retrievers that allow high flow between the retriever and the plenum. This may be a solution to some of the problems but is limited because the retrievers are not grouped and therefore might not perform multiple picks. If multiple picks are attempted then the first pick might fail due to air leakage through the other open cups.
Also, most of the prior art end effectors occupy a large vertical space to accommodate the various hoses for directing the air flow from the retrievers to the vacuum plenum chamber and are heavy and, therefore, tend to be expensive to construct, maintain, repair and/or operate.
Therefore, there exists a need for an improved universal end effector that can be programmed to open vacuum flow to only selected groups of its suction cups as required to form desired patterns or zones of suction, and may be formed in a compact durable configuration. Also, there is a need for an end effector that would allow a high volume of vacuum flow to each suction cup that is to engage the work product substantially without loss of sub-atmospheric pressure of the vacuum source through conduits leading to the suction cups and without complex and restrictive conduits and multiple hoses.